using naci's suggetsion to avoid platform specific code, but use unique "tmpsite" directories.

releng.wtpbuilder/scripts/build/buildutilities.xml

@@ -11,8 +11,10 @@
 	</target>
 	
 	<target name="unpackUpdateJarsAndCreateZippedPackages">
-	    <!-- caution: this tmpsite variable can't be used completely , 'tmpsite' still hard 
-	    	coded at end of this target, due to a bug related to deleting directories -->
+	    <!--Note: we use this odd "tmpsite+archiveName" to make unique directories, since 
+	    	can not be deleted from ant. 
+	    	https://bugs.eclipse.org/bugs/show_bug.cgi?id=142926
+	    	 -->
 		<property name="tmpsite" value="${buildDirectory}/tmpsite-${archiveName}" />